Wiper assembly for step-by-step switches



Y 4 Dec. 28, 1948. v. F. MILLER 'WIPER ASSEMBLY FOR STEP-BY-STEP SWITCES 2 Shets-Sheet 1 Filed Dec,A

' Arrow/5y Dec. 28, 1948. v. F. MILLER '2,457,589

' wIHPER ASSEMBLY FOR sTEP-BLsTE'P-swITHEs Filed Dec. 18, 1946 I 2 sheets-sheet 2 /m/fA/rOR By Il E M/LLER ATTORNEY l pliied form for the sake of clearness. The 'usual Patented Dec. 28V, 1948 .f5

UNITED STATES PATENT OFFICE WiPER ASSEMBLY Foa s'rEP-BY-STEP swrrcnEs Victor F. Miller, Queens Village, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a` corporation of New York Application December 18, 1946, Serial No. 717,053

'6 claims. (ci. y19- 2752) 1y l l 2 This invention relates to electrical switching central wiper carrying shaft I has been shown devices and particularly to improvements in with the vertical ratchet 2. Avertical magnet 3,

switches used for the establishment of connecan armature 4 operated thereby and an actuating tions between subscribers lines in automatic telepawl 5 engaging the ratchet 2 have been shown phone Systems' f 5 for lifting the shaft in a vertical direction.` Be- The object is to simplify and improve from oplow the ratchet 2 is shown a rotary ratchet 6, roeration, installation .and `replacement stand- .tary magnet 1, armature 8 and actuating pawl 9 points, certain partsof automatic switching deengaging the ratchet 6 to rotate the shaft for lovces, i eating the wipers at the desired terminals. Re-

I-Ieretofore in automatic switches, particularlyr l0 lease magnet I0 has been shown with its armaof thestep-by-step type having wiper assemblies ture II and double-dog pawl I2 operated by the and mechanism for guiding such wipers over conarmature I I to release the shaft from an actuated tacts to establish telephoneconnections, the tips position. The retractile spring assembly |3 is of contacting arms of suchrwiper assemblies pass shown attached to the upper end of theshaft I, over successivel contacts in a contact bank of said one end of this spring being connected to the switch. The contacts generallyA are separated shaft and at the other end to the frame I4. from eachother by insulators located below the At the lower end of the shaft I has been shown level of the said contacts, upon'which insulators wiper assemblies I5, |6 and I1 and corresponding the wiper arm tips rest when traveling between banks of terminals I8, I9 and 20 to which concontacts. These wiper arm tips usually vare U- 20 nections may be made by the corresponding wipshaped such that the upturned ends cannot ers being lifted in a vertical direction and then bridge adjacent contacts when the bottom part rotated to engage the desired terminals.v The of the U is resting upon the' aforementioned inusual arrangement is for the wipers I5 to establish sulators. Upon repeated operation of such wiper connections for the sleeve conductors, and wipers arm tips the bottom of the U has become 4worn to 25 I6 and I1 for tip and ring conductor-s. These wipsuch an extentk as to permit the upturned ends of ers are assembled with guide rings 2|, 22 and 23, the U to bridge or short circuit adjacent contacts respectively. Into the guide rings cords 24 may of the contact bank.` be inserted and soldered to projections on the The invention herein set forth provides insulatwipers `as will hereinafter be described. ing means attached to each wiper arm near the Figs. 2 and 3 as previously mentioned are entips thereof and adapted to follow the tips over larged plan and elevation views respectively of the contacts. The insulating means, preferably one of the wipers such as I5 of Fig. l. The main comprising an insulator attached to the wiper ybody 25 of this wiper assembly is constructed of tip, slides across succeeding `contacts to prevent suitable material such as metal having a vise-like the wiper arm tips attached thereto from drop- 'if extension 26 and adapted by means of set screw ping too far below the level of vthe contact sur- 21 threaded in a suitably tapped hole in the body faces so as to create short circuitsor bridgesfbe- 25, to clamp the wiper assembly about the shaft I tween adjacent contacts. 1 i f as shown. The opening in the jaw of this body The invention -has been illustrated in the acmember between the main member 25 and the excompanying drawings in which: tension 26 thereof is dimensionally suited to allow Fig. 1 shows an automatic step-by-step switch the shaft I to be easily inserted therein without of the Strowger type in a simplified form with the requiring relative motion between said body meminvention applied to the wiper assemblies on the berv25 and said shaft I in a direction axial to said shaft, j v v i shaft. In a spring pileup assembly on the wiper Fig. 2 illustrates an enlarged plan view of the 45 body 25 and fastened thereto by means of screws wiper assembly shown in Fig. 1. 28 and 46 are a metal retaining plate 29, a cord Fig. 3 is an elevation offFig. 2 partly in section. guide ring 30, suitable insulating strips 3|, an up- Figs. 4 and 5 illustrate, in connection with subper wiper arm 32, a lower wiper arm 34 and an sequent description, an operating yfeature of the intermediate resilient metallic member 33 which type of wiper assembly disclosed in previous iig- 00 is separated from said wiper arms by means of ures. two of said insulator strips 3|. This member 33 Referring now to the drawings, and particumay be of any suitable resilient material, metal larly to Fig, 1 thereof, the Strowger switchL shown being merely exemplary for the sake of the disin this figure `is illustrated in a somewhat simclosure. The-wiper arms 32 and 34, as illustrated best in Fig, 2, are curved to present the least twisting force to these arms as the wiper assemblies are rotated clockwise as viewed in Fig. 1. The resilient metallic member 33, as best illustrated in Fig. 2, is a straight portion extending directly from the pileup assembly to the proximity of the wiper tips 44 and 45. This member acts not only as a separator for the wipers but also as a damping member to inhibit chatter or rebound of said wipers. In the proximity of the wiper tips, such as 44 and 45 for wiper arms 32 and-3lV respectively, there is riveted or other-wise attached.

to each wiper arm an insulator member such as 4|)` for wiper arm 32, and H for wiper arm 34. These insulators are seen. normally torest upon-memberl 33 by reason of the pretensioningofthe respective wiper arms towards each other. These insulators 40 and 4l are hereinafter referred to as trailing shoes. The guide ring 3U is seen tobe rigidly xed in the pileup assembly and constructed similarly to a split key-ring. The material used for this guide ring is preferably metal and preferably resilient. The projections 3B and 39 represent two free circumferential ends of the guide ring 30 pretensioned to engage each other with appreciable force. These ends are arranged such that by a slight pressure, such as applied by a persons fingers, they will separate to allow cords such as 2t in Fig. l to be inserteditherein.

Heretofore in the art, with reference to Fig. 4, the wiper arms, such 4T and 48'with tips 49 and 50 respectively, when passing across a horizontal group of contacts in such a bank of terminals as illustrated by I8 in Fig. l, have a tendency to wear and present the possibility of short-circuiting contacts such as 54 and 56 or 55 and 5l. The dotted position of wiper tips 49 and 50 shown between contacts 54 and` 56` and between 55 and 51 have been shown. as worn at their contact area to illustrate that this wear may allow. these tips to bridge these contact pairs. The previously mentioned trailing shoes preventy or eliminate possibility of this undesirable condition. As indicated in Fig. 5, the trailing shoes 40 and 4l for wiper arms 32 and 34 respectively have interposed therebetween the resilient metallic member 33. Upon the passing of the wiper tips 44 and 45 across contacts such as 5| and 52 suitable electrical contact will be made thereto. Subsequent to having passed across contacts I and 52, the

wiper tips 44 and 45 will be prevented from dropping too far into the space between contacts, such as between contacts 5l and 54, to thereby eliminate any possibility of short-circuiting these contacts by bridging same as illustrated may happen in previous arrangement as per Fig. 4. It is seen that the trailing shoes 40and 41 provide this feature by respectively resting upon and sliding across contacts 5| and 52 as the wiper tips 44 and 45 leave these contacts.

Referring now to Fig. l, inconnecting the cordsV 24 through the guide rings 2l, 22 and 23 to the respective wiper assemblies, the cord may consist, as shown, of seven individual conductors, All of these are inserted into the lower guide ring 23 and then two of these conductors are connected individually to projections such as 36 and 31 of the wiper I1, these projections being illustrated in Figs. 2 and 3. The remaining conductorsV are inserted into the guide ring 22 and then two of the conductors are connected to the wiper I6 in the same manner. Then an additional conductor is extended to be connected to the special wiper 60; This wiper and corresponding contact bank 6| are provided in certain types of step-bystep switches as is well known. The remaining two conductors are then inserted into the upper guide ring 2| and connected to the wiper l5.

It is readily seen that by reason of the particular type of guide ring disclosed, any number of individual conductors in the cords 24 may be removed from or inserted into any of the guide rings on any, wiper assembly without necessitating removal of either wiper assemblies or rings.

It is also apparent that any wiper assembly such as I5 may be readily detached from the shaft I.. by. virtue of.l its vise-like construction without necessitating removal from said shaft of any other wiper.

It will. readily.y be appreciated by those skilled in the,` artthat wiper assemblies embodying the improvements disclosed herein will lend operating; installationv and maintenance advantages to the switches to which they are applied.

I'he split ring type of cord guide disclosed herein is disclosed and. claimed in my copending application Serial No. '717,052 led December 18, ll946randallowed June 16, 19,48.

What is claimedris:

1; In a switch'. a wiper assembly comprising a body member adapted to be attached to a shaft of* said` switch, two electrically conductive resilient` wiperarms-insulatedly attached to said body memberat one end of each of said two arms, the free ends of said two arms pretensioned to iiex4 toward eachother, a third. arm extending from said body member and extending between the free ends of. said two arms, andan insulating memberattached to each arm near the free end thereof for separating the free end of each of said` twoarms from the extension ofY said third arm, for orientingV said free ends prior to functioning of said free ends and for guiding said freeends during saidfunctioning.

2: In a. switch a wiper assembly comprising a body member adapted to be attached to a shaft of 'said switch, upper and lower electrically conductiveresilient wiper arms insulatedly attached to said body member at. one end of.' each arm, thev freetends of said arms being adjacent and pretensionedto'flex toward each other, said arms having attached to their free ends on respective adjacent surfaces thereof insulating members, and 4an additional resilient member, one end of which is attached to said body member, the free end` of`v which is adapted to` be interposed betweenI said insulating members to separate same and thereby to separate` the said free ends of said Wiper arms, said=insulating members adapted to orient saidfreeends prior to functioning ofr'said free ends and for guiding said free ends during said functioning.

3'. In a switchv a. wiperr assembly comprising a body member adapted to-be attached to a shaft of said switch; upper and lower electrically conductive resilient wiper arms insulatedly attached toA said body member at one end of each arm, the free ends` of said arms being adjacent and pretensioned-to flex toward each other, said arms having attached to their free ends on respective adjacent surfaces thereof insulating members,

and an additional resilient member, one end of which is attached to said-body member, the free end of which is adapted to be interposed between said insulating members to separate same and thereby to separate the said free ends of said wiper arms, said additional resilient member arranged to limit proximity of said arms and insulating-members attached thereto in the normal positions of same butto have no effect on seperation of said arms from each other further than the said normal position, said insulating members adapted to orient said free ends prior to functioning lof said free ends and for guiding said free ends during said functioning.

4. In a switch, a shaft, contact banks, wiper assemblies secured to said shaft, means for actuating said shaft to cause the wipers of said assemblies to engage exposed surfaces of successive contacts in said banks, insulation in said banks for supporting said contacts, said insulation disposed between said contacts and below the level of said exposed surfaces thereof, said wipers adapted to drop below said surface level thereby to engage said insulation when moving between successive contacts in said bank, said wipers constructed such that successive contacts would be bridged thereby if said insulation were not provided as a wiper engaging surface between said successive contacts, said wipers undergoing sufficient wear at the contacting surfaces thereof to enable said wipers to drop further below said surface level to engage said insulation and thereby tending to bridge said successive contacts, and insulating members of said assemblies adapted to engage parts of said banks and arranged to support said worn wipers on said parts when said worn wipers pass between said successive contacts to thereby prevent said worn wipers from dropping further below said surface level and from tending thereby to bridge said successive contacts.

5. In a switch, a shaft, contact banks, contacts arranged in horizontal layers in said banks, wiper assemblies secured to said shaft, means for actuating said shaft to cause each wiper of said assemblies to engage exposed surfaces of successive contacts of a horizontal l-ayer in said banks, insulation in each layer of said banks for supporting contacts of said layers, said insulation disposed between said contacts and below the horizontal level of said exposed surfaces thereof, said wipers adapted to drop below said surface level thereby to engage said insulation when moving between successive contacts in said layer, said wipers constructed such that successive contacts would be bridged thereby if said insulation were not provided as a wiper engaging surface between said successive contacts, said wipers undergoing suicient wear yat the contacting surfaces thereof to enable said Wipers to drop further below said surface level to engage said insulation and thereby tending to bridge said successive contacts, and insulating members attached to said Wipers and adapted to engage contacts of said banks and arranged to support said worn wipers on said contacts when said worn wipers pass between said successive contacts thereby to prevent said worn wipers from dropping further below said surface level and from tending to bridge said successive contacts.

6. In a switch, a shaft, contact banks, contacts arranged in superimposed horizontal arcuate layers in said banks, wiper assemblies secured to said shaft, means for actuating said shaft to cause each wiper of said assemblies to engage exposed surfaces of successive contacts of a horizontal layer in said banks, insulation in each layer of said banks for supporting contacts of said layer, said insulation disposed between said contacts and below the horizontal level of said exposed surfaces thereof, said wipers adapted to drop below said surface level thereby to engage said insulation when moving between successive contacts in said layer, said Wipers constructed such that successive contacts would be bridged thereby if said insulation were not provided as a wiper engaging surface between said successive contacts, said wipers undergoing suflicient Wear at the contacting surfaces to enable said wipers to drop further below said surface level to engage said insulation and thereby tending to bridge said successive contacts, and an insulating member attached to each wiper and adapted to engage the last contact in said layer immediately passed over by said wiper and arranged to support said worn wiper on said last contact when said worn wiper passes between said successive contacts thereby to prevent said worn wiper from dropping further below said surface level and from tending to bridge said successive contacts.

VICTOR. F. MILLER.

REFERENCES CITED Y The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,172,585 Dobbin Feb. 22, 1916 2,259,103 Drake Oct. 14, 1941 FOREIGN PATENTS Number Country Date 37,317 Sweden Aug. 5, 1914 

